I think it was perfectly fine what he said, and it needed to be said, on the World Stage, not just in the minds of people.
And he didn't go as far as what Graham said, basically, "He needs to be assassinated."
I'm not even making a complaint that Graham shouldn't have said that (he shouldn't have...); but that is a bridge too far for President Biden, and he didn't go that far.
"Cannot remain the Russian President" is a truism; and not an outrageous one for Biden to voice. IMO.